Swabs from polymerase chain reaction (PCR) tests, which are sent to labs for analysis, can show if the variant causing the infection looks like Omicron, Delta or something else.

Between a third and a half of UK labs - but not all - have the required technology to detect suspected Omicron cases. That means some parts of the country may identify more Omicron cases more quickly.

Confirming that a suspected case is Omicron requires a full genetic analysis, which takes between four and five days.

PCR tests are the ones you can order free from the government website if you have symptoms, or buy from a private company if you need one for travel purposes. There are many different makes.